In recent years, scanning charged particle beam apparatuses have been widely used in various industrial fields, such as semiconductor field, materials field, medical field and so forth, because of its high spatial resolution. In the observation using the scanning charged particle beam apparatuses, in general, a charged particle beam is irradiated to a sample, and secondary electrons, reflected electrons, etc. emitted from the irradiation position are detected.
As disclosed in Patent Document 1, a secondary electron image indicates contrast mainly reflecting a surface shape of a sample. Moreover, in addition to the surface shape of a sample, a reflected electron image also indicates contrast reflecting its composition. Therefore, by detecting the secondary electrons and reflected electrons in a discriminating manner, various pieces of information of the sample can be obtained. So far, as a method for discriminating the secondary electrons and the reflected electrons, methods have been developed in which a plurality of detectors disposed on the inside and outside of a charged particle beam column are used and in which an energy filtering is carried out by using a multi-pore electrode (Patent Document 2). Moreover, in Patent Document 1, a discriminating method for secondary electrons and reflected electrons by the use of a position sensitive detector is described. Advantages of this method include that an energy filtering can be carried out by using only the single detector.